The present invention relates to a semiconductor integrated circuit, an IC card mounted with the semiconductor integrated circuit, and an operation method for the same, and especially relates to technology which is useful to receive a signal of any one of at least three kinds of reception signals for a short time.
According to the international standard ISO/IEC 14443, an IC card which has a noncontact interface is called a PICC and performs RF communication with a reader/writer called a PCD. ISO stands for the International Organization for Standardization, and IEC stands for the International Electrotechnical Commission. PICC stands for Proximity Card and PCD for Proximity Coupling Device.
For example, as indicated in the following Non-patent Document 1, in Type A of the international standard ISO/IEC 14443, communication from a PCD to a PICC uses a coding system based on a modified Miller method in an ASK 100% amplitude modulation method. However, in Type B of the international standard ISO/IEC 14443, communication from the PCD to the PICC uses a coding method based on an NRZ-L method in an ASK 10% amplitude modulation method. NRZ-L stands for Non Return to Zero-Level. ASK stands for Amplitude Shift Keying, which is one of the digital modulation methods.
For example, as indicated in the following Non-patent Document 2, the international standard ISO/IEC 14443 specifies that a request should be accepted within 5 msec after the PICC goes into an operation field. It is also specified that the PICC of Type A should accept a request command of Type A within 5 msec, regardless of what command of Type B is received. It is similarly specified that the PICC of Type B should accept a request of Type B within 5 msec, regardless of what command of Type A is received.
Further, as described in Non-patent Document 2, in initialization of Type A, the PICC of Type A shifts from an idle state to a ready state by a request command of Type A, and shifts from the ready state to an active state by a select command, and shifts from the active state to a halt state by a halt command. The ready state has an anticollision loop.
As described in Non-patent Document 2 and Patent Document 5 in the following, in initialization of Type B, a PICC of Type B waits for a request command of Type B in the idle state. This request command makes the PICC of Type B be prepared to generate an application family identifier (AFI), an attribute information parameter (PARAM), and a cyclic redundancy check error detection code (CRC). Upon detecting coincidence of AFI, the PICC of Type B transmits a response to the request of Type B to the PCD. This response includes a pseudo unique identifier (PUPI), application information (application data), protocol information, and a cyclic redundancy check error detection code (CRC). Subsequently, upon accepting a PICC select command, the PICC of Type B transmits a response to the accepting to the PCD and shifts to an active state. The transmitting data of Type B is called a character as a frame, and the frame is bounded by SOF (Start Of Frame) and EOF (End Of Frame). Each of SOF and EOF includes one falling edge and the logic “0” of a predetermined length.
In recent years, a short-range wireless communication technology, called Near Field Communication (NFC), has been in widespread use, which realizes consumer-oriented wireless communication connection among home electric appliances and digital media, and simplifies and expands processing of contents and business account. This NFC technology has compatibility with existing various communication methods, and makes it possible to execute the short-range communication at the maximum communication rate of 847 kbps and at the distance of about 10 cm, using an RF frequency of 13.56 MHz. Especially, the NFC technology is mounted in a mobile phone terminal having a built-in IC card microcomputer (secure chip) with an electronic settlement function, aiming at enhancement of the convenience on the side of end users by practical use to various noncontact electronic settlements, such as noncontact payment of the merchandise purchased at a store, noncontact payment of the transportation expenses at a station, etc. NFC stands for Near Field Communication.
Non-patent Document 3 in the following describes the contents of NFC of the international standard ISO/IEC 18092. The communication at a transfer rate of 212 kbps to 424 kbps of NFC of ISO/IEC 18092 employs a coding system based on a Manchester method with the modulation method of an ASK 8 to 30% amplitude modulation. In a passive communication mode, an initiator generates an RF electric field which supplies energy to a target. On the other hand, in the active communication mode, the initiator and the target generate an RF electric field alternately.
In initialization of communication at one of three transfer rates (106, 212, and 424 kbps) of ISO/IEC 18092, the application is switched to the active communicate mode, and one of the three transfer rates is chosen. In initialization of the passive communication mode at a transfer rate of 212 kbps or 424 kbps, a preamble is inserted before a data packet. The preamble includes 48 bits at minimum into which the logic “0” is encoded.
Patent Document 1 in the following describes a noncontact IC card which can be communicated according to an application, by the judgment part of a CPU specifying the modulation method and coding system of a signal which is transmitted from a card reader/writer by following various communication procedure of ISO/IEC 14443.
Patent Document 2 in the following describes a proximity-type noncontact IC card, in which a request signal of Type A of ISO/IEC 14443 is processed by an ASK 100% amplitude demodulation circuit and a modified Miller decoding circuit, and a request signal of Type B is processed by an ASK 10% amplitude demodulation circuit and an NRZ-L decoding circuit. Since one of request signals of Type A and Type B is received and the other request signal is processed erroneously and becomes a meaningless bit string, an arithmetic circuit compares both output values and chooses a signal which is meaningful. An application for arithmetic operation is stored in a nonvolatile memory of the IC card, and a communication method can use either Type A or Type B. However, a priority table of the IC card describes that the priority of Type B is set higher from the reasons of the insufficient margin of the supply voltage due to a reader/writer device, etc.
On the other hand, Patent Document 3 in the following describes a noncontact IC card which includes components such as an antenna coil, a rectifier circuit, a power circuit, a CPU, a demodulator circuit, a modulator circuit, a noncontact control circuit, a ROM, a RAM, and an EEPROM. The components other than the antenna coil are integrated over a silicon substrate. The noncontact control circuit includes a first detector circuit which detects a preamble of a high-speed type, and a second detector circuit which detects SOF of Type B of ISO/IEC 14443. The high-speed type is a header system of the preamble in a Manchester coding method, and Type B is a header system of SOF in an NRZ coding method. A header detection signal of the first detector circuit and a header detection signal of the second detector circuit are supplied to a communication method detecting circuit. The output from the first detector circuit is processed by a first processing by the program execution of the CPU, and the output from the second detector circuit is processed by a second processing by the program execution of the CPU. Execution of useless processing of one of the first processing and the second processing is prohibited by a coincidence detection output signal of the high-speed type or Type B in the communication method detecting circuit.
Patent Document 4 in the following describes a noncontact IC card which distinguishes a long time width of a logical value “0” of the SOF signal added to the top of transmitting data in Type B of ISO/IEC14443 and a short time width of a logical value “0” of the transmission data of the Manchester code of ISO/IEC 18092.    (Non-patent Document 1) D. Baddeley, “Final Committee Draft ISO/IEC 14443-2” Identification cards—Contactless integrated circuit(s) cards—Proximity cards—Part 2: Radio frequency power and signal interface, http://www.waaza.org/download/fcd-14443-2.pdf (searched on May 30, 2008).    (Non-patent Document 2) D. Baddeley, “FINAL COMMITTEE DRAFT ISO/IEC 14443-3” Identification cards—Contactless integrated circuit(s) cards—Proximity cards—Part 3: Initialization and anticollision, http://www.waaza.org/download/fcd-14443-3.pdf (searched on May 30, 2008.)    (Non-patent Document 3) INTERNATIONAL STANDARD ISO/IEC 18092, “Information technology—Telecommunications and information exchange between systems—Near Field Communication—Interface and Protocol (NFCIP-1)”, http://stadards.iso.org/ittf/licence.html (searched on May 30, 2008.)    (Patent Document 1) Japanese Patent Laid-open No. 2008-059271    (Patent Document 2) Japanese Patent Laid-open No. 2003-249870    (Patent Document 3) Japanese Patent Laid-open No. 2006-060363    (Patent Document 4) Japanese Patent Laid-open No. 2006-072678
(Patent Document 5) U.S. Pat. No. 7,364,083-B2, Specification